As a keeper of a couple of Leopard geckos, I thought I'd note that not
all geckos have those atomic-suction feet. Leopard geckos have plain old
feet with old-fashioned claws. They can't walk on walls at all. They can
walk on vertical surfaces if their claws can get hold - stuff like cork,
for example. Most of the Geckos with a species name starting with
"Gekko" (like Gekko gecko or Gekko petricolus) have feet with the atomic
bonding action. Not sure which other species have it. Anyway, not that
any of this really has anything to do with robots... but it is
interesting stuff.

I remember sometime back when they first dicovered
that some geckos were actually bonding at an atomic level with surfaces
they walked on. Makes you wonder if you should worry about a
critical-mass of geckos (or what happens when two geckos touch their
feet together - gecko meltdowns?). There's an article with some close-up
photos of a Tokay's
feet here
for those who are interested in the lizard perspective on the story. :-)